A report from one of Britain's leading experts on the benefits on medical marijuana has urged the British government to relax the laws regarding medicinal use of the drug.

Val Curran, professor of Psychopharmacology at University College London, along with co-author Frank Warburton, says British patients are "suffering unnecessarily" with medicinal marijuana not being made available to them.

The report adds patients with conditions such as multiple sclerosis, spinal cord damage, epilepsy, chronic neuropathic pain, chronic pain following shingles, the side effects of chemotherapy for cancer, and those with a spate of other ailments are being denied effective treatment.

Curran said: "Patients are suffering unnecessarily and others in great pain are travelling abroad to find the cannabis they need to ease their symptoms. All this could change by moving cannabis from Schedule 1 to Schedule 2, thus recognising the medicinal value of the drug. Such a change would also free up research and lead to new medicines for chronic pain, and disease."

Under UK medical regulation, if a drug is in Schedule 1, it is deemed that there are no medicinal benefits to it in spite of the mounting evidence of the possible treatments and pain-killing effects of cannabis. Even heroin is in Schedule 2.

It means the UK is going against the grain when compared with other leading nations such as Canada, the Netherlands, Israel and over 20 states in the US, where herbal cannabis for medical use can be grown under licensed conditions. Germany and Switzerland allow it to be imported from the Netherlands for medicinal purposes.

The report also highlights the fiscal benefits the UK is missing out on. For example, Sativex, the only cannabis derivative available legally in the UK, costs £7,500 per year, with the authors adding "there is extremely limited availability" of this. Bediol, which is a strain of cannabis used as a medicine, costs just a fraction of this at £1,062.15 per annum.

The report concludes: "A logical first step in policy change would be to take cannabis out of schedule 1 and place it in Schedule 2. Schedule 2 status would greatly facilitate research on the medical uses of cannabis, thus stimulating UK medical research into the drug and its constituents.

"An adjustment to the current UK control regime to give patients the right to medication that they believe works for them is unlikely to have any wider impact on the level of recreational cannabis use."

No upsurge in adolescents' use

Meanwhile, allowing the use of medicinal cannabis has not led to an upsurge in the numbers of adolescents using it in the US, says new research.

There are 23 states and the District of Columbia where the use of medicinal cannabis has been approved. In several other states, recreational use is also legal.

Despite believing that this would lead to a rise in use among teenagers, research carried out by Dr Deborah Hasin, professor of epidemiology at Columbia University Medical Center in New York, and her colleagues dismissed these concerns, according to their paper in the journal Lancet Psychiatry.

After analysing data from a national study called Monitoring the Future, which collects information from 50,000 pupils aged 13 to 18 every year, they found there had not been a rise in use.

Dr Hasin said: "Our findings provide the strongest evidence to date that marijuana use by teenagers does not increase after a state legalises medical marijuana. Rather, up to now, in the states that passed medical marijuana laws, adolescent marijuana use was already higher than in other states."

Cannabis breathalyser drug driving
Pro-cannabis campaigners gathered at a \'420 Day Celebration\' at the Hyde Park in London in support of legalising the drug Flickr/ CC

She added: "Because early adolescent use of marijuana can lead to many long-term harmful outcomes, identifying the factors that actually play a role in adolescent use should be a high research priority."

Dr Kevin Hill, from the division of alcohol and drug abuse at McLean Hospital in Belmont, Massachusetts, wrote: "Perhaps the main concern of many people opposed to medical marijuana laws is that they will lead to increased general marijuana use, including among adolescents.

"Hasin and colleagues postulated, as many would, that the passage of medical marijuana laws would increase adolescent marijuana use by contributing to the declining perception of the potential harms of marijuana. Their well-designed, methodologically sound study showed that this was not the case."